Saving Open Land Is All About Density

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This article was originally published in The News Journal (Delaware) on November 2, 2003.

Earlier this year, The News-Journal ran an article headlined "Our vanishing farmland," which detailed the loss of farms in the state as more and more land is developed for housing and commercial and industrial uses.

What that article didn't discuss, and what is generally missing from most discussions concerning farmland and open space preservation, is perhaps the easiest and most important thing that local and county governments can do. The three most important words are: density, density, density.

Like it or not, the population of Delaware has grown tremendously over the past 20 years and will continue to grow. According to the Census Bureau, Delaware's population is expected to grow by 50,000 between 2000 and 2010, and by another 30,000 or more by 2020. Needless to say, these people are going to need places to live, and land for those houses.

The question is not how do we stop this growth? We can't; and even if we could it would be disastrous for the economy.

The real question is how do we maintain farmland and open space while accommodating this growth?

In the world of real estate development, housing density is the number of units one can build on an acre of ground. If, for example, you wanted to develop a 200-acre farm and the permitted density is one unit per acre, that means that you could build at most 200 houses. If the permitted density was two units to the acre, then you build 400 houses on that farm. If the permitted density was three units to the acre, you could build 600 houses.

The higher the density, the less farmland is needed to build the same number of houses. Over a 10- or 20-year period, we can save thousands of acres from development.

If Delaware's population increase over 10 years is expected to be 50,000, and the average household size is 2.5 according to the Census Bureau, that means Delaware will add 20,000 new households over those years. If we have zoning codes that permit an average density of one unit an acre, then we will need 20,000 acres for those 20,000 new homes to be constructed.

However, if we increase permitted densities, the amount of land needed falls dramatically. By increasing average density to two units an acre, we've just saved 10,000 acres from development over a 10-year period. If we increase the density to four units an acre, we would only need approximately 5,000 acres for the same increase in population, and we could save approximately 15,000 acres from development.

At 2-acre minimum lot sizes (the size prevalent in many developments not served by sewer), the average density would be .5 units an acre or less depending on the average lot size, meaning that at least 40,000 acres would be required for the same 20,000 new homes.

The point should be obvious: Higher densities mean less land is developed. The best way we can save farmland in the long run is to allow greater density of development on the farms being developed now.

On a project-by-project basis, it's easy for residents to argue for smaller developments and less dense projects. But in the aggregate, we are cutting off our nose to spite our face. Less density on individual projects simply means more developments, more sprawl, and more loss of open land.

Higher-density have other advantages as well. Among other things, it makes public transit more practical, allows better economies of scale for traffic and other infrastructure improvements, and keeps housing more affordable.

Some people express concern that higher densities result in more crowded development but no savings in land; that we'll still run out of open space. This fear is no reason to prohibit higher-density development now. It just means that density is only one component in good land planning and preservation.

This same logic applies to commercial, office and industrial development. With more restrictive zoning codes now in vogue, nonresidential uses are more limited in their density as well. For example, beyond traditional setback requirements, non-residential projects must provide open space as part of every project. Typically this space consists of patches and strips of grass and shrubs surrounding the buildings or parking lots. Certainly minimal landscaping is needed, but why require relatively large strips of open space surrounding businesses? These areas can't be used by the public and merely cause businesses to need more land for a project and spread out for the same number of stores and offices.

Delaware's farmland preservation program is also important and has been fairly successful. We also need to purchase land for parks and open space. Transfer of development rights is another tool.

But any serious effort to save land must begin with density, density, density.

The more businesses spread out, the more driving customers and employees have to do. Higher-density commercial development means not only less land is used for more stores and businesses, but one need not drive so much.